I. Field
The following description relates generally to wireless communications, and more particularly to sending power control information in a wireless communication system.
II. Background
Wireless communication systems are widely deployed to provide various types of communication content such as, for example, voice, data, and so on. Typical wireless communication systems can be multiple-access systems capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, . . . ). Examples of such multiple-access systems can include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, and the like. Additionally, the systems can conform to specifications such as third generation partnership project (3GPP), 3GPP long term evolution (LTE), ultra mobile broadband (UMB), multi-carrier wireless specifications such as evolution data optimized (EV-DO), one or more revisions thereof, etc.
Generally, wireless multiple-access communication systems can simultaneously support communication for multiple user equipments (UEs). Each UE can communicate with one or more base stations via transmissions on forward and reverse links. The forward link (or downlink) refers to the communication link from base stations to UEs, and the reverse link (or uplink) refers to the communication link from UEs to base stations. Further, communications between UEs and base stations can be established via single-input single-output (SISO) systems, multiple-input single-output (MISO), multiple-input multiple-output (MIMO) systems, and so forth. In addition, UEs can communicate with other UEs (and/or base stations with other base stations) in peer-to-peer wireless network configurations.
In a wireless communication environment, a power control command can be sent on a downlink from a base station to a UE. The power control command sent on the downlink can support uplink power control. Thus, the power control command can cause the UE to increase, decrease, or maintain a transmit power for sending an uplink transmission.
Conventionally, the power control command can be included in downlink control information (DCI), which can be carried by a downlink control channel such as a Physical Downlink Control Channel (PDCCH). The DCI can include downlink or uplink scheduling information and the power control command. For instance, one or two (or more) bits corresponding to the power control command can be embedded in a payload of the downlink control channel (e.g., the PDCCH, . . . ).
Sending the power control command embedded in the payload of the downlink control channel while in various scenarios can be wasteful. For example, if scheduling information need not be provided to the UE, such as when the UE has a persistent assignment or a semi-persistent assignment in the uplink, then employing a format that typically schedules an uplink transmission where the power control command is specified by one or two bits can yield inefficient utilization of resources. According to another example, if a limited number of UEs are activated in a cell, then employing a format that sends group power control for the UEs can similarly result in inefficient utilization of resources.